1. Field of the Invention
The present invention relates to a composition and process for manufacturing chewing gum in a single compounding step.
2. Description of the Prior Art
Commercially useful chewing gum is made, for the most part, from a preformed chewing gum base which is compounded with various combinations of bulk sweeteners, modifying agents, intense sweeteners, coloring agents, flavorants and other materials. The chewing gum base, itself, is preformed from various combinations of masticatory materials, which are usually elastomeric polymers, plasticizers for the elastomer, detackifiers, plasticizers for the detackifiers, oleaginous materials such as waxes and fatty materials, mineral fillers and antioxidants.
The types, and amounts, of the various components used in making such chewing gum products, are disclosed, for example, in U.S. Pat. Nos. 4,452,820 and 4,525,363.
The manufacture of such prior art products thus requires the use of relatively large numbers of different components, some of which are used in one compounding procedure, i.e., for making the gum base, and others are, subsequently, used with the preformed gum base, in a second compounding operation, for making the desired chewing gum product.
These prior art gum base compounding procedures are usually conducted at elevated temperatures of about 200 to 280.degree. F., and at steam pressures of about 0 to 70 psi, and require processing times of about 60 to 180 minutes, essentially because of the facts that the elastomer components of such systems have relatively high viscosities and melting points and relatively low glass transition temperatures. Thus, even when melted, they are difficult to process in conventional mixing equipment.
U.S. Pat. No. 3,440,060 discloses chewing gum products based on the use therein of certain co- and ter-ethylene vinyl acetate polymers containing, in weight %, about 1 to 40% ethylene, optionally, about 1 to 15% of a vinyl ester of a long-chain fatty acid, and the remainder, vinyl acetate. The chewing gum compositions made with these ethylene-vinyl acetate co-/ter-polymers were made in a one-step mixing operation under undefined conditions. Because of the poor characteristic physical properties of the ethylene-vinyl acetate co-/ter-polymers, and the poor gum formulation, used in making the chewing gum products disclosed in this patent, however, such chewing gum products have little or no current commercial utility because they are too brittle, and are difficult to process.
U.S. Pat. No. 3,473,933 discloses making a gum base composition by first polymerizing vinyl proprionate in the presence of some or all of the commonly used gum base components, and then separately compounding the thus preformed gum base with the remaining components of the chewing gum composition. This chewing gum making procedure also requires a multi-step compounding operation.
Certain polyvinyl acetate resins have also been used as the sole polymeric component of chewing gum products as disclosed, for example, in West German Patent No. 2,830,324 and Belgian Patent No 686,750.
Product brochures of Wacker Chemie GmbH, D-2000 Munich 22, Federal Republic of Germany, relating to their Vinnapas resins indicate that their vinyl acetate homopolymers and copolymers of vinylacetate with vinyl laurate are approved for use in chewing gum by the Federal Republic of Germany.
Attempts by the present inventors, however, to make useful chewing gum products using the Vinnapas copolymers in the formulations and one-step mixing procedures of U.S. Pat. No. 3,440,060 were unsuccessful in that unchewable, difficult-to-process chewing gum products were made.
It has not been possible, therefore, prior to the present invention to readily prepare commercially useful chewing gum products in a single compounding operation, at relatively low temperatures, with relatively few compounding materials, while employing vinyl resins as the sole polymeric component of such compositions.
An object of the present invention is to provide a composition and process for readily making commercially acceptable chewing gum products in a single compounding step wherein such compositions contain various vinyl resins as the major functional polymeric component thereof.
A further object of the present invention is to make chewing gum products that are shelf-stable, i.e., do not harden during storage, and in stick form, they remain flexible.